1. Field of Invention
This invention relates to the manufacture of semiconductor thin-film, and more particularly to polycrystalline semiconductor thin-films formed on dissimilar substrates.
2. Description of Related Art
In general, polycrystalline thin-film transistors are fabricated on substrates that are capable of withstanding high temperature processes such as, for instance, processes that take place at temperatures higher than 500° C. However, unlike traditional amorphous silicon thin-film transistors, poly-silicon devices usually perform best only when a silicon oxide gate dielectric is used. Silicon oxide of high quality is generally obtained through a deposition process that takes place at high temperature, which precludes the use of substrate materials, on which the silicon oxide is deposited, that have low melting or decomposition temperatures or that would not withstand high temperatures. These substrates are, for instance, plastic substrates.
Accordingly, the conventional method of manufacturing polycrystalline silicon thin-film transistors on materials that do not withstand high temperatures such as, for instance, flexible materials or plastic platforms, generally involves using low temperature deposition process in order to deposit amorphous silicon, which is later re-crystallized in order to form polycrystalline silicon using, for instance, localized laser irradiation. The silicon oxide gate dielectric is then deposited on the flexible plastic platform using a low temperature deposition process. However, thin-film transistors formed in this manner generally exhibit poor performance because of the poor dielectric properties of the transistor.